Jenson Button sealed the drivers’ championship with a sublime recovery drive at a dramatic Brazilian Grand Prix won by Red Bull’s Mark Webber.
Brawn’s English driver started from 14th but executed a series of spectacular early overtaking moves before finishing the race fifth.
He was already set to clinch the crown when a late puncture dropped main title threat Rubens Barrichello to eighth.
Brawn still took the constructors’ championship in their debut season.
Barrichello, who badly wanted to win on a circuit he was born in the shadow of, was running third before his unlucky puncture smoothed team-mate Button’s path to the title he seemed destined for since his explosive start to the season.
BMW Sauber’s Robert Kubica was second ahead of McLaren’s Lewis Hamilton while six drivers retired at Interlagos.
Red Bull’s German Sebastian Vettel, who started just behind Button, finished fourth while Toro Rosso’s Sebastien Buemi was a season-best seventh.
Button’s maiden world title overshadowed the grand prix, but the race certainly delivered a fitting scene for a deserved success.
With the stands bubbling over with atmosphere, anticipation was sky-high at the Sao Paulo track where the world championship has now been decided in the past five years.
And the drama began as soon the race got under way.
Barrichello made a rapid start while Ferrari’s Kimi Raikkonen jumped up to third using his energy-boost (Kers) button before suffering front-wing damage in a frenetic first lap.
But a contentious first-lap collision took out Toyota’s Jarno Trulli and Force India’s Adrian Sutil and led the pair to engage in a furious argument at the side of the track – both blaming the other. The crash also took out Renault’s Fernando Alonso.
Seconds later, in the pits, McLaren’s Heikki Kovalainen pulled away with the fuel hose still attached to his car.
The leaking fuel immediately caught fire right in Raikkonen’s face, although it quickly died away and both Finn were able to rejoin the race.
All the while 29-year-old Button had managed to steer clear, literally, of any trouble to jump up into ninth place after starting the race down in a potentially-disastrous position near the back of the pack.
Buoyed by another stroke of luck in a season in which he has worked so hard for it, he fearlessly set about improving his position with a superb display of bravery and surgeon-like precision once the safety car came in on lap six.
Charging Button first used persistence to take Romain Grosjean’s Renault on the outside to move into eighth before eating up the Williams of Kazuki Nakajima to go seventh and then quickly setting about Toyota’s Kamui Kobayashi.
The Japanese Formula 1 debutant defended strongly.
But Button, who had been losing time to Barrichello and Webber up front, used all his nous to dummy himself into a clever pass on lap 24.
Barrichello, meanwhile, had not quite managed to put enough space between himself and Australia’s Webber and the Brazilian lost the lead during the first pit stops.
His hopes of victory faded immediately as he was overtaken by Vettel after rejoining and then got caught up in traffic.
Button continued his aggressive approach despite having moved into a decent position, and after pitting on lap 29 he managed to execute another overtaking manoeuvre as he crucially slipped past Buemi.
Nakajima careered off the track at the end of the back straight on lap 31 after Kobayashi moved over on him.
At this point Webber was clocking fastest laps for fun and team-mate Vettel was driving superbly well, both drivers pushing their impressive Red Bull cars to the limit.
Button – who won six of the first seven races of 2009 but has endured a tough second half of the season – met the test of nerve he faced until the finish head on and in style, unlocking a flood of emotion as he crossed the finish line.
“The last few races have been a bit stressful for me, especially qualifying,” a jubilant Button told BBC Sport.
“But that race today, to me, was worthy of becoming world champion. Kobayashi is absolutely crazy, very aggressive. It was a great race, really enjoyable. That was the perfect way to do it.”
On 89 points, Button heads to Abu Dhabi on 1 November with an unassailable lead in the championship while Vettel has leapfrogged Barrichello into second on 74 with the Brazilian now on 72.
“It was a great car to drive all year,” said Barrichello. “Jenson won it and deserved it but he won it in the first six or seven races.
“The second half of the season was mine… and I fought really hard. I’m pleased for Jenson as a friend and as a great champion.”
Hamilton started the race from back in 17th but the man who now hands over his world crown to compatriot Button was typically aggressive as he made the most of the circumstances that he encountered to finish on the podium.
Race stewards are investigating the crash between Sutil and Trulli, along with an incident involving Ferrari’s Giancarlo Fisichella and Kovalainen’s mishap in the pits.